And for Transportation Alternatives, the bicycle and pedestrian advocacy group, it was supposed to be a time to celebrate. A fund-raising party in Boerum Hill, Brooklyn — complete with a choreographed “Bike Ballet” — was set for Aug. 23, a date chosen early this summer and meant to occur long after the bikes had rolled out.

The party will go on. But, with Labor Day looming, the city’s bike-share program, to be the largest in the country and once promised for July, has not yet hit the streets.